Duration of Availability of Tritiated Thymidine Following Intraperitoneal Injection

1968 ◽  
Vol 3 (1) ◽  
pp. 89-93
Author(s):  
W. K. BLENKINSOPP
Keyword(s):  
Cell Division ◽  
Intraperitoneal Injection ◽  
Deoxyribonucleic Acid ◽  
Direct Evidence ◽  
Tritiated Thymidine ◽  
Indirect Evidence ◽  
Acid Synthesis ◽  
Single Intraperitoneal Injection ◽  
Deoxyribonucleic Acid Synthesis

Much indirect evidence supports the assumption that tritiated thymidine does not label cells which enter the deoxyribonucleic acid synthesis phase (S) more than 1 h after injection. Direct evidence confirming this assumption was obtained by counting labelled epithelial nuclei in mice killed 1, 4 or 6 h after a single intraperitoneal injection of [3H]thymidine; colchicine was used to prevent the increase in number of labelled nuclei which would otherwise have occurred because of cell division. The proportion of cells labelled was the same at 1 h as at 4 or 6 h after injection of [3H]thymidine. Nuclei were regarded as labelled if they were overlaid by 4 grains or more; comparison of nuclear and background labelling indicated that nuclei overlaid by 3 grains or less represented background labelling.

Cell Proliferation in the Epithelium of the Oesophagus, Trachea and Ureter in Mice

1969 ◽  
Vol 5 (2) ◽  
pp. 393-401
Author(s):  
W. K. BLENKINSOPP
Keyword(s):  
Cell Cycle ◽  
Deoxyribonucleic Acid ◽  
Single Injection ◽  
Tritiated Thymidine ◽  
Acid Synthesis ◽  
Basal Cells ◽  
Paraffin Sections ◽  
Cell Cycle Time ◽  
Deoxyribonucleic Acid Synthesis ◽  
Intermediate Cells

Over a 24-h period, groups of mice were given a single injection of colchicine (to collect blocked metaphases) and tritiated thymidine (to label nuclei synthesizing deoxyribonucleic acid). Epithelial nuclei in the oesophagus, trachea and ureter were examined and counted in paraffin sections: the duration of deoxyribonucleic acid synthesis (Ts) was calculated from the numbers of blocked metaphases and labelled nuclei, the duration of the post-synthetic gap (TG2) was estimated from the proportion of blocked mataphases labelled, and the cell cycle time (Tc) was calculated from Ts and the proportion of nuclei labelled. In each epithelium the different layers seen by light microscopy were analysed separately. Ts was probably the same for the basal and superficial cells in the trachea (about 8 h), and was probably the same for the basal, intermediate and superficial cells in the ureter (about 5 h). In the oesophagus Ts was 8.5 h. TG2 was probably the same for the basal and superficial cells in the trachea (3.6 h), and probably the same for the basal, intermediate and superficial cells in the ureter (about 4.6 h). In the oesophagus TG2 was 2.8 h. Tc was about 380 h (basal cells) and 1400 h (superficial cells) in the trachea, and about 8000 h (basal and intermediate cells) and 2700 h (superficial cells) in the ureter. In the oesophagus Tc was 41 h.

scholarly journals DURATION OF PREMEIOTIC DEOXYRIBONUCLEIC ACID SYNTHESIS AND THE STAGES OF PROPHASE I IN RABBIT OOCYTES

1970 ◽  
Vol 47 (3) ◽  
pp. 577-584 ◽  
Author(s):  
J. J. Kennelly ◽  
R. H. Foote ◽  
R. C. Jones
Keyword(s):  
Dna Synthesis ◽  
Meiotic Prophase ◽  
Deoxyribonucleic Acid ◽  
Tritiated Thymidine ◽  
Acid Synthesis ◽  
Prophase I ◽  
Meiotic Prophase I ◽  
Maximum Duration ◽  
Deoxyribonucleic Acid Synthesis ◽  
Silver Grains

To estimate the duration of oocyte DNA synthesis 36, 3-day-old female rabbits received 3, 6, 9, 12, 15, or 18 injections of tritiated thymidine (thy-3H) at hourly intervals. The ovaries, removed at 1, 10, or 20 days after the first injection, were radioautographed. Counts made of the number of silver grains associated with oocyte nuclei in meiotic Prophase I indicate that the duration of DNA synthesis is between 9 and 12 hr. To determine the length of the stages of meiotic Prophase I, a group of 2-3-day-old rabbits was given a single sub-cutaneous injection of thy-3H, and the ovaries were removed at hourly and/or daily intervals after treatment. The minimum duration of leptotene was 3 hr and the maximum duration probably was less than 8 hr. The maximum durations of zygotene, pachytene, and diplotene were estimated to be 44, 216, and 96 hr, respectively. The interval from the end of oogonial DNA synthesis to the beginning ofpremeiotic DNA synthesis (G2 + Mitosis + G1) appeared to be less than 6 hr.

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